This revised application aims at establishing an international collaborative research program on Parasitic Diseases in Africa. The objective is to apply modern biomedical and epidemiological tools to study specific aspects of host-parasite relationship in schistosomiasis, bancroftian filariasis and echinococcosis. The proposed interdependent and multidisciplinary studies will address 1) the determinants of specific features of the outcome of infection and 2) the utilizations of this understanding to favor the human host. A series of field, population based and laboratory investigations are proposed. The application is organized in three projects addressing specific aspects of each infectious disease and two cores to coordinate the administrative and immunological aspects of these studies. The major objectives of these projects include studies of: Project 1: Examination of the immune response to S. haematobium infection and its relationship to age, intensity of infection and effect of chemotherapy. Project 2: Effect of W. bancrofti infection in mothers on filariasis immunopathology in offspring. Project 3: Determine the natural history and spectrum of immunologic responses to defined native and recombinant parasite antigens in echinococcosis. The program is a natural outcome of long standing collaborative efforts between U.S.-based and Kenyan-based investigators. It will provide information necessary to shape control strategies and further opportunities for training and technology transfer.